Conventionally, a night-vision device mounted to a vehicle, so-called “a night-vision system” is known (refer to PTL 1). The night-vision device of this type includes a projector that emits near infrared rays to a specified space defined around the vehicle, an image pickup device receiving light including the near infrared rays from the specified space to generate an image, and a display device displaying the image picked up by the image pickup device.
Some of the night-vision devices of this type detect an object to be detected such as a pedestrian on the basis of the image picked up by the image pickup device, and inform the presence of the object to be detected.